从数据库中获取值后通过文本框更新值不起作用

Question

我们正在从数据库中获取值并在页面加载时显示文本框，然后在更新时，该页面的点击事件不起作用并自动重定向到母版页。我们需要更新那些在数据库中获取的值。

public partial class pages_update : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        int id = Convert.ToInt32(Request.QueryString["id"].ToString());
        if (!Page.IsPostBack)
        {

            // txtname.Text = this.txtname.Text;
            SqlConnection connection = new SqlConnection(@"Data Source=.\SQLEXPRESS;Initial Catalog=studreg;Integrated Security=True");
            DataTable dt = new DataTable();
            connection.Open();
            SqlDataReader iReader = null;

            /*
            if (id != 0)
            {
                if (!this.IsPostBack)
                {
                txtname.Text = id;
                //msg_lbl.Text = "Inside not PostBack";
            }
        }
        else
            Response.Write("Invalid URL for article");
        */


        string images = Request.QueryString["image1"];
        SqlCommand cmd = new SqlCommand("select id,(cast(fname as varchar(10))+''+cast(mname as varchar(10))+''+cast(lname as varchar(10)))as concatenated ,qualification,collage,dob,image,address,contact,email, technology from studreg", connection);
        iReader = cmd.ExecuteReader();
        int status = 0;
        while (iReader.Read())
        {
            int chkid = int.Parse(iReader["id"].ToString()); ;

            if (id == chkid && status == 0)
            {
                status = 1;
                // txtid.Text = (iReader["id"].ToString());
                txtname.Text = (iReader["concatenated"].ToString());
                txtqualification.Text = (iReader["qualification"].ToString());
                txtcollage.Text = (iReader["collage"].ToString());
                //  txtgender.Text = (iReader["gender"].ToString());
                txtdob.Text = (iReader["dob"].ToString());
                string path = string.Concat(@"/internship/pages/images/", iReader["image"].ToString());
                Image1.ImageUrl = path;
                txtaddress.Text = (iReader["address"].ToString());
                txtcontact.Text = (iReader["contact"].ToString());
                txtemail.Text = (iReader["email"].ToString());
                txttechnology.Text = (iReader["technology"].ToString());
             //   break;
            } //end if
        } // end while

    } // ennd ispostback

} // page load
//  connection.Close();




//protected void UPDATE_Click(object sender, EventArgs e)
protected void UPDATE_Click(object sender, EventArgs e)
    {

        SqlConnection connection = new SqlConnection(@"Data Source=.\SQLEXPRESS;Initial Catalog=studreg;Integrated Security=True");
        SqlCommand cmd = new SqlCommand("update studreg set qualification=@qualification,collage=@collage,dob=@dob,address=@address,contact=@contact,email=@email,technology=@technology where id=@id", connection);

        if (connection.State != System.Data.ConnectionState.Open)
        {
            connection.Open();
            // cmd.Parameters.AddWithValue("@concatenated", txtname.Text);
            cmd.Parameters.AddWithValue("@qualification", txtqualification.Text);
            cmd.Parameters.AddWithValue("@collage", txtcollage.Text);
            cmd.Parameters.AddWithValue("@dob", txtdob.Text);
            cmd.Parameters.AddWithValue("@address", txtaddress.Text);
            cmd.Parameters.AddWithValue("@contact", txtcontact.Text);
            cmd.Parameters.AddWithValue("@email", txtemail.Text);
            cmd.Parameters.AddWithValue("@technology", txttechnology.Text);
            //   cmd.Parameters.AddWithValue("@id", txtid.Text);*/
            //SqlCommand cmd = new SqlCommand(sql, con);
            cmd.ExecuteNonQuery();
            //cmd.ExecuteNonQuery(); 
            //  lblmsg.Text = "Successfully updated";
        }
        else
        {
            connection.Close();
        }
    }
}

按钮：

<asp:Button ID="UPDATE" class="btn btn-info pull-right" runat="server" Text="UPDATE" onClick="UPDATE_Click" ></asp:Button>

Answer 1

据我所知，您没有将在WHERE 部分上定义的@id 参数值添加为where id = @id。看来您需要取消注释该行；

// cmd.Parameters.AddWithValue("@id", txtid.Text);*/

如果不需要，或者删除命令中的@id参数。

还有一些事情；

• 使用using statement 自动处理您的连接和命令，而不是手动调用Close 方法。
• 尽量不要使用AddWithValue。 It may generate unexpected results sometimes。使用Add 方法重载来指定您的参数类型及其大小。

using(var connection = new SqlConnection(conStr))
using(var cmd = connection.CreateCommand())
{
    // Define your CommandText
    // Add your parameter values with Add method
    // Open your connection
    // Execute your query 
}

注意，您将所有参数添加为文本。根据它的名称，id 列应该是数字类型，而不是字符。